Study On Preparing Low-cost Coblat Free Black Ceramic Pigments

Using nickel sesqui oxide,chromic oxide,ferric oxide,copper oxide,manganese dioxide as raw materials, a kind of low-cost black pigments, which presents pure relatively black color at high temperature, is obtained through a series of optiumization experiments. It's a type of ceramic pigments which shows color indensity data L*=27.49,a*=1.21,b*=1.45. This type of pigments which can present pure relatively black color at high temperature with its compositional ranges as follows: nickel sesqui oxide 37, chromic oxide 31, ferric oxide 42, copper oxide 7, manganese dioxide 7 and magnesium oxide 3wt%. In order to further reduce the cost, a kind of lower cost coblat free black pigments, which also presents pure relatively black color at high temperature, is obtained through introducing the industrial waste including copper cement-tailings and chromite replacing part of chemical raw materials. It's a type of ceramic pigments which shows color indensity data L*=28.26,a*=1.82,b*=1.35. This type of pigments which can present pure relatively black color at high temperature with its compositional ranges as follows: nickel sesqui oxide 37, chromic oxide 21～26, ferric oxide 33.4～35.2, copper oxide 7, manganese dioxide 7 ,copper cement-tailings 11.8～23.6, chromite 10.2～20.4 and magnesium oxide 3wt%.X-ray diffraction (XRD) and uv vis absorption spectrum(UV )analysis show that type ceramic pigments which present black color is due to transition metal ions forming complex spinel phases. Introducing copper cement-tailings and chromite to the samples leads to the changes of unit cell constant and unit cell volume, which cause the changes of photon absorbing intensity and hue. Cooling ways act on pigment color performance, according to the degree of size: quenching-in water > air quenching > furnace cooling. Quenching-in water keeping the transition metal ions sprawling distribution at high temperature and lattice distortion increasing is the main reason of light intensity. The color indensity data are also affected by soaking time. With extending soaking time, the degree of crystal is better and L* value is increscent while a*and b* is lower. So, the optimal soaking time was 60 minutes in this study.